<template>
  <div>
    <router-link
      tag="div"
      to="/"
      class="header-abs"
      v-show="showAbs">
      <div class="iconfont header-abs-back">&#xe624;</div>
    </router-link>
    <div
      class="header-fixed"
      v-show="!showAbs"
      :style="opacityStyle"
    >
      <router-link to="/">
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
export default {
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  methods: {
    handleScroll () {
      const top = document.documentElement.scrollTop
      if (top > 60) {
        let opacity = top / 140
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = { opacity }
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  },
  mounted () {
    window.addEventListener('scroll', this.handleScroll)
  },
  unmounted () {
    window.removeEventListener('scroll', this.handleScroll)
  }
}
</script>

<style lang="stylus" scoped>
@import '~styles/varibles.styl';

.header-abs {
    position: absolute;
    left: 10px;
    top: 10px;
    width: 40px;
    height: 40px;
    border-radius: 20px;
    text-align: center;
    line-height: 40px;
    background: rgba(0, 0, 0, 0.8);
}

.header-abs-back {
    color: #ffffff;
    font-size: 20px;
}

.header-fixed {
    z-index 2;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: $headerHeight;
    line-height: $headerHeight;
    text-align: center;
    color: #ffffff;
    background: $bgColor;
    fontsize: 16px;
}

.header-fixed-back {
    position: absolute;
    top: 0;
    left: 0;
    width: 32px;
    text-align: center;
    font-size: 20px;
    color: #ffffff;
}
</style>
